Assignment 7

library(readr)
library(plotly)

## Loading required package: ggplot2

## 
## Attaching package: 'plotly'

## The following object is masked from 'package:ggplot2':
## 
##     last_plot

## The following object is masked from 'package:stats':
## 
##     filter

## The following object is masked from 'package:graphics':
## 
##     layout

hr <- read_csv('https://raw.githubusercontent.com/aiplanethub/Datasets/refs/heads/master/HR_comma_sep.csv')

## Rows: 14999 Columns: 10

## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr (2): Department, salary
## dbl (8): satisfaction_level, last_evaluation, number_project, average_montly...
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

Task 1

cor.test(hr$time_spend_company, hr$satisfaction_level)

## 
##  Pearson's product-moment correlation
## 
## data:  hr$time_spend_company and hr$satisfaction_level
## t = -12.416, df = 14997, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  -0.11668153 -0.08499948
## sample estimates:
##        cor 
## -0.1008661

Task 2

The results of the correlation test indicate that there is a statistically significant weak negative correlation between time_spend_company and satisfaction_level. The p-value of less than 2.2e-16 indicates that this result is highly significant; we can reject the null hypothesis that there is no correlation between the two variables.

Task 3

There is a slight tendency for employees who spend more time at the company to report lower satisfaction levels. The relationship is weak, but suggests that long-term employees might feel less satisfied over time. The very low p-value indicates that this finding is statistically significant, meaning it is unlikely to have occurred by chance. Therefore, it’s worth considering that as employees stay longer, their satisfaction may decline.

Task 4

library(ggplot2)
ggplot(hr, aes(x = time_spend_company, y = satisfaction_level)) +
  geom_point() +  
  geom_smooth(method = "lm", color = "blue", se = FALSE) +  
  labs(title = "Longer Tenure with the Company Tends to Lower Satisfaction",
    x = "Years at the Company",
    y = "Job Satisfaction Level") 

## `geom_smooth()` using formula = 'y ~ x'